Method of making diamond tools



Oct. 16, 1951 s s 2,571,772

METHOD OF MAKING DIAMOND TOOLS Filed May 20, 1949 INVEN TOR. ABRAHAM S/MONS.

A fforneys.

Patented Oct. 16, 1951 UNITED STATES PATENT OFFICE Claims. 1

My invention relates to a new and improved diamond tool and a new and improved method of maki g such tool. When I refer to a diamond tool, I include a tool which has particles or pieces which are made of cutting or abrading or grinding material or other material.

The invention relates particularly to a dental tool which is used for grinding or shaping teeth, including cavities in teeth, in making inlays, etc.

The invention applies to other types of diamond tools, such as grinder wheels, etc. and to other types of tools.

It is well known to bind or fix diamonds to the metal body of a tool, by a metal binder layer, which can be formed by electro-deposition.

When such tools are used in dental work, the tooth material, such as the tooth enamel or dentine, or the material of amalgam fillings oi the teeth, fills the spaces between the diamonds and covers the diamonds, thus clogging the tool and making it useless.

I eliminate this disadvantage and produce other advantages, as later explained herein.

Fig. 1 is a sectional view of an improved tool prior to finishing, the diamonds being shown in elevation; and

Fig. 2 is a similar view of the finished tool.

Without limitation, the invention is explained with reference to a dental tool which uses diamond particles, and the invention is not limited to the illustrative details explained herein or to the materials disclosed herein.

In this example, the diamonds D are of 100-140 mesh, as one example, in the U. S. standard specifications for sieves, in which No. 100 corresponds to a sieve opening of 0.149 millimeter or 0.0059 inch, and sieve No. 140 corresponds to 0.105 millimeter or 0.0041 inch. Hence the average particle size of the diamond particles D is substantially 0.004 to 0.006 inch.

The size of the diamonds D will depend upon the type of work or tool.

I mix the diamonds D intimately with frit particles E, which are preferably and optionally of the same or substantially the same size as the The uniform mixture of diamonds D and frit particles E may be made at ordinary temperature of 20 C.-25 C. and in any suitable mechanical device. The diamonds D and frit particles E may be dry while said mixture is made, thus producing an intimate and uniform dry mixture. As an alternative, the particles can be mixed with water or other wetting liquid. If mixed with water, the wet mixture may be put into the bath.

This mixture of dry or wet particles is then put into an aqueous electroplating bath, to form a layer of particles D and E which contains equal parts by volume of diamonds D and frit particles E. The height of this layer may be 0.5 inch. The aqueous electroplating bath is held in a tank of insulating in? serial, such as a methyl methacrylate resin, of the type known as "Lucite." The tank may be made of rubber or other insulating material.

The body or shank I of the tool may be of suitable conductive material, such as stainless steel or other metal or alloy.

As one example, the shank or body I may be cylindrical. In general, it may be shaped to have a longitudinal axis.

This shank I is lowered into the layer of diamonds D and particles E, so that said layer contacts with or envelops the entire zone or part of the shank or body I which is to be provided with the diamonds D. as the operating head or part of the tool. This shank, which may be cylindrical,

is held vertical during the electroplating.

The layer of intermixed diamonds D and particles E rests upon a silk sieve or fabric or other permeable and non-metallic material, which is held fiat and horizontal, a suitable distance above the bottom wall of the tank. A horizontal and flat metal anode of uniform thickness is located on the inner face of the bottom wall of the tank. In this example, a nickel binder layer M is formed by electrodeposition, and I use an aqueous nickel electroplating bath of any suitable type and a nickel anode. Said bath fills the tank up to the top of the layer of diamo ds D and frit particles E, if desired, above the top of said layer to any desired height.

While the shank I is held vertical, with its lower end at the permeable and non-conductive horizontal support for the layer of mixed particles, the horizontal nickel anode is connected to the positive terminal of a source of unidirectional current, and the vertical shank is connected to the negative terminal of said course, in order to form a vertical binder layer M of electrodeposited nickel on the selected part of the the height of the bath may be selected so that the top of the bath is at the top of the final electrodeposited layer M, when this has its desired final height or thickness.

In the preferred partly finished embodiment, and as shown in Fig. l, the diamonds D and frit particles E are alternately radially located, so that there is one frit particle E between each pair of diamonds D. It may be impossible to secure this ideal condition, but I can approximately secure this ideal condition up to at least ninety per cent. Therefore, the diamond particles D may abut each other at one or more areas of the tool, said diamond particles D may abut frit particles E at one or more areas of the tool, and said frit particles E may abut each other at one or more areas of the tool. The nickel or other metal binder layer M is formed to a thickness of substantially 65 %-'75% of the height or particle size of the diamonds D and the frit particles E, whose inner parts are embedded in this electrodeposited metal binder layer M. It is noted that the inner ends of the frit particles E, and also of the diamonds D, touch the shank or body I. In this embodiment, diamonds D and frit particles E are radial relative to the longitudinl axis of the shank or body i. 1

The partly finished tool, constructed as shown in Fig. 1, is now withdrawn from the bath and the partly finished tool is heated to fire the frit particles E and produce final spacer enamel particles Ea, shown in Fig. 2, which have inner body parts Eb and outer layer parts E0. The inner enamel bod parts Eb retain substantially their original shape, and they are intimately bound or fixed to the metal layer M.

As one example, the tool is heated to 1200 F. to 1500 F., depending upon the composition of the frit. This heating may be done in an enclosed electric furnace, which may have an air atmosphere or an inert atmosphere.

The exposed parts of the frit particles E spread laterally as a result of the firing, to form the outer lateral heads Ec of the final spacer enamel particles Ea. These enamel heads Ec preferably but not necessarily contact intimately with the diamonds D, inwardly of the exposed ends of diamonds D.

It is very difilcult to anchor enamel to metal, particularly nickel or stainless steel, particularly when using small particles of frit to form final small particles Ea of enamel.

However, tests have shown that by partially embedding frit particles E as disclosed herein, and then laterally spreading the exposed parts of the frit particles by firing, I secure a very firm and intimate union between the final enamel particles Ea and the respective adjacent areas of the surfaces of the nickel layer M and thus bond the final enamel particles Ea firmly to the nickel at all parts of said enamel particles Ea. Thus I fill or substantially fill the spaces between the diamonds D with a smooth enamel layer Ec.

If the diamonds D touch each other, or are mediate particles, the tool packs or clogs readily, because the tooth material, amalgam, etc., clings to the metal shank I or to the initially deposited layer of metal on said shank l between the diamonds D.

Tooth material and amalgam are substantially,

non-adherent to enamel. That is, while tooth material and amalgam and gold may cling to enamel, such clinging material is easily removed by washing with gentle friction or brushing. On the other hand, such materials cling so firmly to nickel, as one example so that they cannot be removed by ordinary mashing or scrubbing or brushing.

I thus provide a simple method whereby the diamonds D are suificiently spaced from each other in a uniform and reliable manner, so that the cutting or grinding efficiency of the tool is increased, in addition to providing enamel spacer particles E0. in the finished tooth, to which the material of the tool or other work is not adherent. By properly spacing the diamonds D from each other, I secure greater efficiency with a smaller number of diamonds, thus decreasing the cost of the tool.

While I prefer to use enamel spacer particles which have been fired in situ, the invention is not limited thereto. During the firing, the shank of the tool is preferably held vertical, with its coated part either at the top or bottom of the shank, so that the exposed material of the spacer particles E will flow laterally uniformly to form enamel heads Ec.

The shank I of the tool may be horizontal during the firing, if said shank is rotated about its horizontal axis slowly, in order uniformly to distribute the fiow of the exposed material of the spacer particles E.

While I greatly prefer to provide fired enamel spacer particles Ea in the finished tool, I do not limit the invention thereto. Thus the material of the original spacer particles E may be a suitable resin such as a phenol-aldehyde resin or resin of the phenol-aldehyde type, and it may be any other material, such as a thermo-plastic or thermo-setting resin, which can fiow as above described, at a temperature at which the diamonds are not injured or seriously injured. The diamonds D may be of the usual industrial type, such as borts or carbonados. The invention'also applies if the diamonds D are replaced by cutting or grinding or abrasive particles made of other materials, such as boron carbide, corundum, and other fused-alumina materials of the aluminum oxide type. Also, the particles or pieces D may be of any type, to do any kind of work.

In the finished tool, and as shown in Fig. 2, the diamonds D or other particles are partially exposed.

By increasing the volume proportion of the original spacer particles relative to the volume of the cutting or grinding or abrading or other.

particles D, I can regulate the spacing between said particles D in the finished tool. In some cases, it is desirable to have a greater or less spacing than as illustrated herein.

I can also regulate the characteristics of the final tool by using spacer particles E of greater or less size than the particles D, and also by regulating the volume proportion between particles D and the spacer particles.

The particles D are generally designated as working elements or members. They may be of any size, so that when I refer to particles, I do not limit the elements or members D to any size.

very close to each other, without spacing by inter- (5 The parts Ec may be designated as the enlarged lateral heads of the bodies Eb of the final spacer particles Ea. wholly or at least partially in the binding layer M, and said heads Ec preferably contact intimately with the respective adjacent areas of the outer surface of the binding layer M. As above noted, said lateral heads Ec optionally, but not necessarily contact with the elements D. Preferably said heads Ec wholly or substantially laterally fill the spaces between the elements or members D, inwardly of the exposed end-parts of elements D.

If desired, the shank I can be provided with a thin initial coating or nickel or other metal, at the zone of said shank where the elements D and E are to be located and afilxed, prior to forming the finishing binding or bonding layer M.

The invention is not limited to the materials which are disclosed herein as illustrative examples.

This application discloses an improvement over my application Serial No. 63,699, filed in the U. S. Patent Office on Decrmber 6, 1948, now abandoned. Reference is made to said application Serial No. 63,699 as part of the disclosure herein.

Thus, when I refer to an enamel, I include a vitreous enamel or glaze which adheres firmly to the metal bonding layer M and which preferably has the same coefficient of thermal expansion as the metal of the bonding layer M, within a range of 20 C.-100 C. Reference is also made to the disclosure of the compositions of the frit particles E in said prior application, without limiting the invention to such compositions. I have found that by the improved method disclosed herein, I can use ordinary commercial frits.

The bonding layer M may be formed in any manner.

Also, the invention includes the subcombinations of the complete combination disclosed herein. As one sub-combination, the device may consist of a ring or other hollow body M, without the shank i.

I prefer to use frit particles E, whose embedded portions shown in Fig. 1 increase in volume during the firing, so that the embedded enamel bodies Eb make intimate contact with the bond-- ing layer M. That is, prior to firing, the embedded portions of frit particles E contact with the walls of the corresponding cavities in bonding layer M to a greater or less extent. As a result of the firing, the volume of the embedded enamel bodies Eb is increased relative to the volumes of said cavities, thus producing a very firm and intimate bonding. The invention is not limited to this, because the volume of an embedded enamel body Eb may be equal to or even slightly less than the volume of the original embedded part of the frit particle E.

Also, the invention is not limited to providing the enlarged heads Eb, although this is preferred. That is, the frit particlespr other spacer particles or elements E may be made smaller than the working elements D, so that the spacer elements E are completely embedded in the initial stage of Fig. 1. Upon firing, the resultant enamel or other spacer elements will be substantially embedded in the body M with exposed faces at the surface of body M, but without enlarged heads Ee. Said body M will then have small exposed surface areas around the projecting parts of working elements E. Such exposed surface areas of body M will be sufficiently small, so that the Said bodies Eb are embedded clogging tooth material or other clogging material will not cling to such exposed surface areas of body M or such clogging material can be easily removed. In such case, the spacer particles E have exposed faces or surface areas at the exposed surface of body M, to provide surface areas which are non-adherent to the clogging material.

. As above noted, there may be a plurality of spacer elements E between adjacent working elements E. The exposed surface areas of the exposed or working surface of body M may be smaller than the exposed surface areas of spacer elements E in the disclosed embodiment, if the heads Ec are omitted, or if the spacer elements E are of smaller size than working elements D, and the heads Ec are omitted.

When I refer to embedded particles or elements D and E, I include any means or method of fixing said elements D and E to the body M.

Numerous other changes and omissions and additions and substitutions can be made without departin from the scope of the invention.

I claim:

1. A method of making a tool which has a conductive body with the use of a mixture of working elements in particle form and frit particles, which consists in locating said mixture in an electroplating bath whose liquid is located in the spaces between said particles, locating the body of said tool in said mixture to be enveloped by said mixture and said bath, passing a current through said bath between said conductive body and an anode to form an electrodeposited binding layer on said body in which said working elements and frit particles are only partially embedded to form a partly finished tool in which said working elements and frit particles project beyond said binding layer, and then heating said tool to fire said frit particles and to spread the projecting parts of said fired frit particles alon the outer surface of said binding layer between the projecting parts of said working elements.

2. A method of making a tool which has a conductive body with the use of a mixture of working elements in particle form and frit particles, which consists in locating said mixture in an electroplating bath whose liquid is located in the spaces between said particles, locating the body of said tool in said mixture to be enveloped by said mixture and said bath, passing a current through bath between said conductive body and an anode to form an electrodeposited binding layer on said body in which said working elements and frit particles are only partially embedded to form a partly finished tool in which said working elements and frit particles project beyond said binding layer, and then heating said tool to fire said frit particles, said tool being heated to a firing temperature sufiiciently high to laterally spread the exposed parts of said frit particles during the firing and to bind said laterally spread and exposed parts to the exposed face of said binding layer.

3. In the art of making a tool which has a conductive body with the use of a mixture of working elements in particle form and frit particles, those steps which consist in locating said mixture in an electroplating bath whose liquid is located in the spaces betwen said particles, locating the body of said tool in said mixture to be enveloped by said mixture and said bath, passin a current through said bath and an anode to form an electrodeposited binding layer which binds said work elements and frit particles to said body, and then firing said frit particles, said 7 frit particles being provided in suflicient proportion to provide uncoated fired frit particles between substantially all said working eelments.

4. A tool which has a tool-body, a binding layer of metal bonded to said tool-body, said metal binding layer having an outer face, diamond working elements which are spaced from each other, said diamond working elements having inner portions which are embedded in and bonded to said metal binding layer, said diamond'i vorking elements having outer portions which extend outwardly of said outer face of said metal bindin layer, spacer members, said spacer members having inner shanks which are embedded in and bonded to said metal binding layer, said spacer members having spacer heads which are located outwardly of said outer face of said metal binding layer, said spacer heads being enlarged laterally relative to said shanks, said spacer heads having inner head-faces which abut and are bonded to said outer face of said metal binding layer, said spacer-heads also having outer headfaces, said outer portions of said diamond workin elements extending outwardly beyond said outer head-faces, said spacer heads substantially covering the portions of said outer face of said metal binding layer intermediate said outer portions, said spacer members being made of nonmetallic material which softens and is spreadable at a temperature which is below the disintegration temperature of said diamond working elements and the melting temperature of said tool-body.

5. A tool which has a tool-body, a binding layer of metal bonded to said tool-body, said metal binding layer having an outer face, dia- 8 mond working elements which are spaced from each other, said diamond working elements having inner portions which are embedded in and bonded to said metal binding layer, said diamond working elements having outer portions which extend outwardly of said outer face of said metal binding layer, spacer members, said spacer members having inner shanks which are embedded in and bonded to said metal binding layer, said spacer members having spacer heads which are located outwardly of said outer face of said metal binding layer, said spacer heads being enlarged laterally relative to said shanks, said spacer heads having inner head-faces which abut and are bonded to said outer face of said metal binding layer, said spacer-heads also having outer headfaces, said outer portions of said diamond working elements extending outwardly beyond said outer head-faces, said spacer heads substantially covering the portions of said outer face of said metal binding layer intermediate said outer portions, said spacer members being made of enamel.

ABRAHAM SIMONS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 604.569 Ringstrom May 24, 1898 842,993 Archer Feb. 5, 1907 2,319,331 Kurtz May 18, 1943 2,360,798 Seligman et al Oct. 17, 1944 2,367,286 Keeleric Jan. 16, 1945 

